The peak wavelength of the radiation which is produced in a single active region of a laser diode chip frequently has a significant temperature response, that is to say it varies with the operating temperature of the active region. In the case of laser diodes based on gallium arsenide, the peak wavelength typically changes by approximately 0.3 nm/K. The operating temperature is generally governed primarily by the loss heat which occurs during radiation production, with the quantity of loss heat depending on the conversion efficiency of electrical power to radiation power in the active region of the laser diode, in the case of electrically pumped lasers.
In the case of laser diode arrangements having a plurality of active regions, different active regions may be at different operating temperatures. This can lead to an increase in the differences between the peak wavelengths of the radiation produced in the respective active regions, or may be a reason for the occurrence of such differences.